ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
Copyright to IJIRSET www.ijirset.com 15324
Optimization of Cycle Time for Wire Harness
Assembly β Line Balancing and Kaizen
Approach
Aasheet Kumar1, Gaurav Chaudhary
2, Manish Kalra
3, Binit Kumar Jha
4
U. G. Student, Dept of Manufacturing Technology, J.S.S. Academy of Technical Education, Noida, U.P, India1
U. G. Student, Dept of Manufacturing Technology, J.S.S. Academy of Technical Education, Noida, U.P, India2
U. G. Student, Dept of Manufacturing Technology, J.S.S. Academy of Technical Education, Noida, U.P, India3
Head of Department, Dept of Manufacturing Technology, J.S.S. Academy of Technical Education, Noida, U.P, India4
ABSTRACT: As the customer needs product at higher quality, shorter delivery time, higher customer service level and
lower price; companies adopt continuous productivity and quality improvement to survive in the increasingly
competitive world market. To cater to this, line balancing and kaizen are effective approaches to improve the
productivity and quality. This paper has made use of these approaches to improve the productivity on a Wire Harness
Assembly line of a company manufacturing wire harnesses for automobiles. Here, the balance rate has been calculated
before and after improvement to show the reduction in manpower requirement and increase in output.
KEYWORDS: Kaizen, Assembly Line balancing, Wire harness, Waste reduction, Takt time
I. INTRODUCTION
Kaizen is defined as a cycle of continuous improvements focusing on analysing the performance, brain storming
improvement opportunities, implementing improvement and measurement to gauge process, documentation of new
standard operating procedure and then repeating the cycle. Continuous improvements require that the company
continually strive to be better through learning and problem solving. Because we can never achieve perfection, we must
always evaluate our performance and take measures to improve it.
Assembly line balancing and sequencing is an active area of optimization research in operations management. The
concept of an assembly line came to the fact when the finished product is inclined to the perception of product
modularity. Usually interchangeable parts of the final product are assembled in sequence using best possible design of
logistics in an assembly line. The initial stage of configuring and designing an assembly line is focused on cost efficient
mass production of standardized products.
The primary focus of line balancing is minimizing waste related to over production, inventory, defects,
transportation, motion, waiting. Assembly line balancing is the only way to achieve that. Principle of inter
changeability and division of labour brought about the concept of assembly line, the primary aim of the assembly line
was to facilitate mass production, standardisation, simplification and specialisation. Besides, assembly line was also
useful in dividing complex work structures into a number of elemental tasks, which would simplify the complex
assembly. Assembly line balancing also provides flexibility to the employees, thereby reducing the monotonous
activity and thus improving job satisfaction. From the manufacturing point of view, the foremost advantage of
assembly line balancing is the ability to keep the direct labour busy doing productive work. Generally an assembly line
is designed for high volume production of single item or a family of items.
ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
Copyright to IJIRSET www.ijirset.com 15325
In present day manufacturing, an assembly line can be formed easily for any industry be it small scale or large scale
industry. When the takt time are calculated for every assembly operation in the like through different part movements,
then the problem of locating required location on the shop floor occurs in all time
II. LITERATURE REVIEW
M. Bala Kumar et al.[1] focused on improving the productivity of a Compressor assembly plant by reducing the
cycle time by identifying non-value adding activities on the assembly line and eliminating them using lean tools. Artun
TΓΆrenli [2] in his thesis analysed the operations and balance losses at the pre-assembly line in a bus production system
at MAN TΓΌrkiye A.Ε. He intended to create a framework for the restructuring process that optimized resource
utilization. In the study, an assembly line was observed and analyzed in order to evaluate the balance losses and their
reasons. Eventually it was determined which operations were inappropriate for the line and the most evident of them
were eliminated. Gautham J. et al. [3] concentrated on improving the overall efficiency of a single model assembly line
by reducing the non-value adding activities, cycle time and distribution of work load at each station by line balancing.
The methodology they adapted included calculation of process cycle time, identifying non-value adding activities,
calculating the total work load on each station and distributing it by line balancing to improve the efficiency of the
assembly line. Prashant Uttam Bagal et al. [4] conducted a pilot study of the assembly line to estimate the line
imbalance, which was further followed by waste identification, waste elimination and de-bottlenecking of the line to
optimize the utilization of resources. Layout was modified to switch from batch and queue system to single piece flow.
Sarvesh Kumar Srivastava et al. [5] developed a low cost automation system using a lean tool Kaizen i.e. continuous
improvement. It is then seen how low cost automation in manufacturing industry is useful for productivity
improvement, fatigue reduction and reduction the chances of injury.
.
III. PROBLEM DEFINITION
High productivity is what we seek in an assembly line; hence we need to determine the optimum amount of resources
in terms of workstation and labour. One method of having a higher productivity assembly line is to use line balancing.
Line balancing tool can help to characterize line capacity and take into account the dynamic behaviour of the system.
Line balancing can also assist in implementing changes in a quick and effective manner. It is also able to evaluate and
optimize the line throughput, machine utilisation and cycle time. This work deals with the end to end perspective of
reducing waste at a wire harness assembly line of a manufacturing company. This study is done in wire harness
assembly line.Workers are moving all the time to search for tools and materials. This occurs mainly due to keeping
resources far away from the work place.
The purpose of assembly line balancing is:
1. Increase productivity by eliminating waste and reducing variation
2. Standardize the improvement method and develop it globally
3. Train personnel that are able to find and improve problems by themselves
During assembly, various losses are observed. The losses are caused due to:
1. Line unbalance
2. Deviation
They are graphically shown below in figure 1.
ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
Copyright to IJIRSET www.ijirset.com 15326
Figure 1. Losses observed
Figure 2. Methodology
IV. METHODOLOGY APPLIED
For implementing the line balancing and kaizen in wire harness assembly, the sequence of process and methodology is
explained in the figure 2 and table 1.
Direction of
Improvement Item Computation tool Criterion
Improvement
achieved
Distance
ratio from πΆπ to
π΄π£π max
π΄π£ππππ₯β πΆ π
πΆπ
Γ 100
Distance ratio
from πΆ π to π΄π£π
max Bottleneck
Improvement
(More than 10% or 0%)
Line
balance rate
ππ’ππππ‘πππ ππ ππππ π π‘ππ‘πππ ππ£π π‘πππ
πππ₯πππ’π ππ£π π‘πππ Γ ππ’ππππ ππ π π‘ππ‘ππππ Γ 100
Line balance rate Line Balance
Improvement (Less than 70%)
Proper
manpower
ππππππ ππππππ€ππ=π΄πππππ£ππππ ππππππ€ππβππππ πππ‘ ππππππ€ππ
π΄πππππ£ππππ ππππππ€ππ
=ππ’ππππ‘πππ ππ ππππ π π‘ππ‘πππ ππ£π π‘πππ
πΆπππ£ππ¦ππ π ππππ π‘πππ
Difference
Manpower Proper
Manpower
Improvement More than 1
person
Table 1: Improvement Sequence
ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
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TAKT TIME
It sets the pace for industrial manufacturing lines so that production cycle times can be matched to customer demand
rate. In practice, it is generally understood that cycle time needs to be slightly less than takt time.
ππππ‘ π‘πππ =πππππ’ππ‘πππ π‘πππ ππ£πππππππ
πΆπ’π π‘ππππ π·πππππ
LINE BALANCE RATE (LBR)
The line balance rate (LBR), and the related line balance loss rate (which is simply 100% minus the LBR), quantifies
how well or poorly the line is balanced.
ππ’ππππ‘πππ ππ ππππ π π‘ππ‘πππ ππ£π π‘πππ
πππ₯πππ’π ππ£π π‘πππ Γ ππ’ππππ ππ π π‘ππ‘ππππ Γ 100
V. EXPERIMENTAL RESULTS
The process of wire harness assembly requires various processing stations like sub-assembly, final assembly, clamping,
circuit, part fitting etc. A pictorial representation has been shown in figure 3.
Figure 3. Assembly Line
A. PRESENT STATUS
For various activities the time has been calculated by using stopwatch. The time required by each processing station is
shown in figure 4.
ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
Copyright to IJIRSET www.ijirset.com 15328
Figure 4. Time study graph Sub-Assembly & Final Assembly combined
During time study following is identified:
1. Improvement is required for balance rate.
2. Total numbers of kaizen identified (to be implemented) are 32, distributions are shown in figure 5
3. Maximum time is wasted in crossing of wire & during the mounting of the assembly.
4. Present balance rate: ππ’ππππ‘πππ ππ ππππ π π‘ππ‘πππ ππ£π π‘πππ
πππ₯πππ’π ππ£π π‘πππ Γ ππ’ππππ ππ π π‘ππ‘ππππ Γ 100 = 54.3%
5. 4-M contributions are shown in figure 6
Figure 5. Kaizen Distribution Figure 6.4-M contributions
B. AFTER STUDY AND IMPROVEMENT THROUGH LINE BALANCING AND KAIZEN During the assembly process, two types of assemblies are done:
1. Sub-Assembly
2. Final Assembly
For each of them, time study is represented in tabular and graphical form in table 2, figure 7 and table 3, figure 8
respectively.
25%
28%
47%
Type of Kaizen
Cycle Time Reduction
Improved Balance Rate
Variation Reduction
25%
19%
6%
50%
4-M Contributions
Man Machine Material Method
ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
Copyright to IJIRSET www.ijirset.com 15329
WS
SEQ. 1 2 3 4 5
TAKT
TIME AVG
AVG
MAX. MIN MAX
STD
DEVIATION
LINE
BALANCE
RATE
S/A. 1 35 35 30 38 32 77 34 48 30 38 3
S/A. 2 28 26 30 31 30 77 29 48 26 31 2
S/A. 3 38 36 32 39 32 77 35.4 48 32 39 3
S/A. 4 26 33 27 30 25 77 28.2 48 25 33 3
S/A. 5 36 35 38 35 34 77 35.6 48 34 38 2
S/A. 6 35 44 45 39 37 77 40 48 35 45 4
S/A. 7 49 47 44 46 54 77 48 48 44 54 4
S/A. 8 20 22 23 22 23 77 22 48 20 23 1
S/A. 9 28 27 25 27 28 77 27 48 25 28 1
S/A. 10 36 40 51 48 64 77 47.8 48 36 64 11
S/A. 11 25 23 23 27 23 77 24.2 48 23 27 2
TOTAL 371.2 528 330 420 3 0.703
Table 2: Sub-Assembly time study
The above results show the line balance rate improvement via kaizen from 54.3% combined to 70.3% for sub assembly
as it can be seen in table 2 and shown in a graphical representation in figure 7.
Figure 7. Sub-Assembly time study graph
WS. SEQ. 1 2 3 4 5
TAKT
TIME AVG
AVG
MAX. MIN MAX
STD
DEVIATION
LINE
BALANCE
RATE
F/A. 1 75 77 85 74 85 77 79.2 83.6 74 85 5
F/A. 2 63 69 67 68 75 77 68.4 83.6 63 75 4
F/A. 3 76 65 68 64 78 77 70.2 83.6 64 78 6
F/A. 4 74 87 69 63 63 77 71.2 83.6 63 87 10
F/A. 5 56 67 62 56 58 77 59.8 83.6 56 67 5
F/A. 6 45 43 44 48 46 77 45.2 83.6 43 48 2
F/A. 7 65 43 44 58 51 77 52.2 83.6 43 65 9
F/A. 8 39 40 36 42 30 77 37.4 83.6 30 42 5
F/A. 9 58 46 42 43 48 77 47.4 83.6 42 58 6
F/A. 10 43 46 41 44 43 77 43.4 83.6 41 46 2
F/A. 11 45 42 40 46 46 77 43.8 83.6 40 46 3
F/A. 12 76 67 69 77 65 77 70.8 83.6 65 77 5
F/A. 13 37 32 32 34 35 77 34 83.6 32 37 2
ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
Copyright to IJIRSET www.ijirset.com 15330
CLAMP 82 86 88 82 80 77 83.6 83.6 80 88 3
CKT. 56 52 68 61 59 77 59.2 83.6 52 68 6
PART
FITTING 36 39 37 41 35 77 37.6 83.6 35 41 2
VISUAL
INSPECT. 35 39 50 39 41 77 40.8 83.6 35 50 6
TOTAL 944.2 1421.2 858 1058 5 0.664
Table 3: Final Assembly time study
Table 3 shows the line balance improvement for final assembly to 66.4% and shown in graphical form in figure 8.
Figure 8. Final Assembly time study graph
VI. ACKNOWLEDGEMENT
We are grateful to M/S Motherson Sumi Systems Ltd. (MSSL), NOIDA for supporting us and allowing us to
conduct the experiments at their facility.
VII. CONCLUSION
1. The balance rate calculated for present status is found to be 54.3% for both Sub-Assembly and Final Assembly
combined.
2. The balance rate calculated after the implementation of Line Balancing and Kaizen is found to be 70.4% for
Sub-Assembly and 66.4% for Final Assembly.
3. As a result a greater extent of line balancing has been achieved.
4. Due to improvement in balance rate, the needed manpower has been reduced by increasing the output from a
single assembly line.
REFERENCES
[1] M. Bala Kumar, D. Rajenthirakumar, "Improving Productivity in Assembly line by reducing cycle time β Kaizen Approach", Proceedings
of National Conference on Manufacturing Innovation Strategies & Appealing Advancements", Vol.4, pp.1-7, 2013
[2] Artun TΓΆrenli, "Restructuring and balancing of the bus pre-assembly line at MAN Nutzfahrzeuge AG Ankara factory", Masterβs Thesis in
the International Masterβs programme Automotive Engineering, Chalmers University of Technology, 2009.
ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 3, Issue 8, August 2014
DOI: 10.15680/IJIRSET.2014.0308036
Copyright to IJIRSET www.ijirset.com 15331
[3] Amardeep, T.M. Rangaswamy, Gautham J, "Line balancing of Single Model assembly line", International Journal of Innovative Research
in Science, Engineering and Technology, Vol.2, Issue 5, , pp.1678-1680, 2013
[4] Prashant Uttam Bagal, Shriram M. Sane, Varsha N. Karandikar, "Line balancing on Wiring Harness Assembly Line: A case study",
International Journal of Current Engineering and Technology, Vol.4, Issue 2, pp.968-973, 2014
[5] Sarvesh Kumar Srivastava, Dr. R.M. Belokar, Mudit Jaithalia, Akash Verma, Kuldeep Singh, "Application of Kaizen for Low Cost
Automation in Automobile Assembly Line to improve productivity: A Case Study", International Conference on Advanced Research in
Mechanical Engineering, Vol.5, pp.46-49, 2013